Preparation of aluminum monohydride diethoxide



United States Patent 3,524,870 PREPARATION OF ALUMINUM MONOHYDRIDEDIETHOXIDE Norman E. Matzek, Midland, and William H. Crawford,

Gladwin, Mich., assignors to The Dow Chemical Company, Midland, Mich., acorporation of Delaware No Drawing. Filed Dec. 8, 1967, Ser. No. 688,993Int. Cl. C07f /06 US. Cl. 260-448 1 Claim ABSTRACT OF THE DISCLOSURE Neworganoaluminum compounds and their method of preparation wherein thecompounds correspond to the formula H AlfOC H where n and n are theintegers 1 and 2 and wherein when either one of n or n is 1 the otherinteger is 2.

The novel compounds are useful as reducing agents, especially in organicchemical reactions. They can also be used as an aluminum source materialfor the plating of metallic aluminum onto various substrate materials.

The compounds can be prepared by reacting aluminum ethoxide withaluminum trihydride in an inert solvent to obtain a mixture of saidcompounds and reacting ethanol and aluminum trihydride in an inertsolvent to obtain aluminum monohydride diethoxide.

SUMMARY OF THE INVENTION New compounds corresponding to the formula riAltoc m-g wherein n and n are the integers l and 2 and wherein wheneither one of n or n is equal to 1 the other integer is 2.

The compounds can be prepared either by reacting aluminum trihydride andaluminum ethoxide in an inert solvent to obtain a mixture of saidcompounds and separating aluminum dihydride monoethoxide from saidmixture, or by reacting ethanol and aluminum trihydride in an inertsolvent to obtain aluminum monohydride diethoxide.

The novel compounds are white crystalline solids having a unique X-raydiffraction pattern consistent with the above indicated structures.

PREFERRED EMBODIMENTS In the actual practice of the invention, usuallyan ether solution of ethanol, or solid aluminum ethoxide is added to another solution containing aluminum trihydride and the solutioncontaining the reactants is agitated for a sufficient period of time toallow a substantially complete reaction to occur. Conveniently, theproduct precipitates from the reaction mass and readily is separatedfrom the residual solution. Allowing the reaction mixture to stand oragitate for a prolonged period of time, i.e. 2 to 3 hours or more, hasnot been found to be detrimental to the products.

Ordinarily, following the reaction period, the ether solution isconcentrated to assure optimum precipitation of the ethoxide producttherein and the product removed by conventional separation methods, e.g.filtering under reduced pressure, and dried by evaporation.

The present compounds are ordinarily prepared under an inert,substantially anhydrous atmosphere such as, for example, nitrogen orargon.

The inert solvent usually employed is an alkyl ether and includes, forexample, diethylether, n-dipropyl ether,

diisopropyl ether, tetrahydrofuran, and other like solvents. Thereaction is usually carried out at relatively mild temperatures, i.e.from about 20 to about 33 C. although higher or lower temperatures, atwhich the solvent is liquid, can be employed.

The reactants are ordinarily provided in about stoichiometric amountsfor the preparation of the desired product.

The concentration of the solutions is not critical. Maximumconcentrations are those such that the reactants are completelydissolved therein at the operating conditions. Extremely dilutesolutions are not desired because of the difiiculty of handling. Also,with such dilute solutions considerable time is required for formationand precipitation of desired products.

The following examples will facilitate a more complete understanding ofthe present invention but are not meant to limit it thereto.

Example l.Preparation of aluminum dihydride monoethoxide Solid aluminumtriethoxide [(C H O) Al] (8.1 grams) was slowly added to 500: ml. ofdiethyl ether solution, 0.2 molar with respect to aluminum trihydride.The reaction mixture was stirred for about two hours whereupon a whitecrystalline solid precipitated. The solid was separated from the solventby filtering and dried under a reduced pressure.

The White solid was washed with a diethyl ether solution whereupon partof the solid dissolved into solution. Upon evaporation of the diethylether solution a white crystalline solid precipitated. Elementalanalysis of this product gave C, 30.7 percent; H, 9.0 percent; A1, 36.3percent and O, 24.0 percent. Calculated theoretical analysis foraluminum dihydride monoethoxide, (C H O) AIH is C, 32.45 percent; H,9.45 percent; Al, 36.45 percent; and oxygen, 21.65 percent.

X-ray powder diffraction gave a heretofore unknown pattern as presentedin following Table I.

In Table I d represents the interplanar spacings of the plans in A.based upon Miller indices and I/If is the relation line intensitycompared to the strongest line based at 100.

The product is soluble in diethyl ether.

Example 2.-Preparation of aluminum monohydride diethoxide To 500 ml. ofdiethyl ether solution, 0.1 molar with respect to aluminum trihydride,at room temperature was added 200 ml. of diethyl ether, containing 0.3cc. of ethanol. The solution was stirred for three hours and allowed tostand for about 20 hours whereupon a white 3 crystalline precipitate wasobserved. The precipitate was separated from the solution and dried.

Elemental analysis of the solid product for carbon, hydrogen, oxygen andaluminum showed the elements to be present in the proper ratio for thecompound aluminum monohydride diethoxide corresponding to the formula (CH O AlH.

X-ray powder diifraction gave a heretofore unknown pattern as presentedin following Table II.

The d and U1 values are on the same basis as for Example I.

The product was insoluble in diethyl ether.

Various modifications may be made in the present invention withoutdeparting from the spirit or scope thereof for it is understood that weare limited only as defined in the appended claim.

What is claimed is:

1. A process for producing aluminum monohydride diethoxide whichcomprises:

(a) contacting ethanol with aluminum trihydride under an inertsubstantially anhydrous atmosphere and in the presence of an inertsolvent; and

(b) reacting the reactants for a suflicient period of time such thatmonohydride diethoxide is formed.

References Cited UNITED STATES PATENTS 3,060,216 10/ 1962 Hamprecht etal. 3,147,272 9/1964 Brown et a1. 3,281,443 10/ 1966 Hunt. 3,405,15410/1968 Lundeen et al. 3,435,059 3/ 1969 Schmidt et al.

FOREIGN PATENTS 1,246,620 10/ 1960 France.

TOBIAS E. LEVOW, Primary Examiner H. M. S. SNEED, Assistant Examiner

